JP2691179B2 - Printing film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film capable of offset printing using a normal drying oil type ink. [Prior art] Conventionally, printing and patterning on a resin film have been performed by gravure printing, flexo gravure printing, screen printing, etc., in which a wide range of printing inks can be selected and an ink that is familiar with the film can be selected. . However, these printings have some drawbacks such as a high plate-making cost and poor workability, poor gradation of a printed image, and the image is likely to be unclear. On the other hand, in offset printing, the cost of making a plate can be reduced easily and easily, and the gradation of an image is good and clear. Therefore, it has been desired to be able to print on a plastic film by offset printing. Generally, offset printing uses inks that contain colorants, resins, drying oils, high-boiling petroleum solvents as the main ingredients, and additives such as wax compounds and dryers. Ink absorption cannot be expected at all. Therefore, the setting of the ink is extremely slow. In particular, when printed on a sheet-shaped film, the films are piled up until the drying and curing due to the oxidative polymerization of the ink are incomplete, and the ink is transferred to the outside and smeared by bleeding. In extreme cases,
This will cause a blocking phenomenon. In order to prevent such a situation, a method has been adopted in which offset printing is performed on a resin film using an ultraviolet curable ink or an electron beam curable ink, and the ink is cured by irradiating ultraviolet rays or an electron beam immediately after printing. Was. However, this method requires expensive devices such as an ultraviolet ray generator and an electron beam generator, and particularly in the case of multi-color simultaneous printing,
A UV generator or the like must be provided for each color printing. Therefore, the feature of offset printing that can be reduced in cost is reduced by half. Further, ultraviolet curable inks have a unique unpleasant odor even after the ink is dried due to the influence of a reaction initiator and residual monomers, and many of them have problems in safety and health. When performing offset printing on sheet-like film,
In addition to the above-mentioned consideration of ink absorbency and dry-curability, as a general characteristic, the stacked films are smoothly sent to the printing machine one by one, with good registration accuracy and discharged to be completely aligned and stacked. It is necessary to be piled up. That is, the running property of the film must be good. Therefore, it is necessary to prevent the stacked films from frictionally charging and tacking, reduce the surface friction coefficient, and prevent blocking due to heat history and humidity history during film storage. Conventionally, an interleaving paper having good slipperiness is overlapped on the back surface of the film, and a part of the interleaving paper is temporarily fastened with an adhesive, a pressure-sensitive adhesive, a double-sided adhesive tape, or the like so that the film and the interleaving paper do not shift during traveling. However, this method is troublesome in the work of temporarily fixing and removing the temporary fixation, and uses extra slip sheets. On the other hand, in JP-A-54-96590, a polyester film coated with an acrylic copolymer composition having a quaternary ammonium salt on a side chain soluble in water or an aliphatic lower alcohol is disclosed as an offset film. It is described that the film is suitable for printing. However, according to the follow-up test conducted by the present inventors, it was found that the polyester film coated with the above substance has good wettability with the offset ink for sheet, but has a low ink drying and fixing speed.
Since the surface electric resistance of the coating film formed on the film is suppressed and triboelectric charging is unlikely to occur, it is possible to prevent running defects caused by static electricity such as tacking. However, acrylic copolymer compositions containing these quaternary salts have poor moisture resistance and heat resistance. An experiment was conducted in which sheets of the polyester film coated with the above substances were stacked and stored. As a result, it was found that moisture was absorbed even in a normal room at room temperature to cause a blocking phenomenon, and that poor running was likely to occur. Further, general properties required for a printing film such as scratch resistance and abrasion resistance are not satisfactory. [Problems to be Solved by the Invention] The present invention has been made in view of the above, and by fixing the surface of a film, the fixability of ink, that is, the adhesion (wetting) of ink, absorbency and dry curing Good nature,
Moreover, it provides an optimal film for offset printing that has excellent running properties and that also satisfies the properties generally required for printing sheets such as heat resistance, moisture resistance, scratch resistance, and abrasion resistance. Is. [Means for Solving Problems] A printing film, which is a first invention for solving the above problems, has a rubber resin latex or / and a styrene resin latex as a main component on at least one surface of a plastic film. An ink fixing layer formed by coating as is provided and fine irregularities are formed. A printing film, which is a second invention for solving the above problems, has an ink fixing layer formed by applying a rubber-based resin latex or / and a styrene-based resin latex as a main component on at least one surface of a plastic film. It is provided, has fine irregularities, and is further subjected to a conductive treatment. Examples of the base plastic film include polyester film, polyolefin film such as polyethylene film and polypropylene film, polycarbonate film, triacetate film, polyether sulfone (PES) film, polyether ether ketone (PEEK) film, vinyl chloride film,
There are various acrylic films such as methyl methacrylate and cellophane films. Among them, a polyester film, a polypropylene film or a triacetate film is preferable. The plastic film whose adhesiveness has been improved by a sinking treatment may be used. Examples of the rubber-based resin composition constituting the ink fixability include styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, and methacrylic acid ester-
Butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, methacrylate-styrene-
Butadiene copolymers or substituted derivatives thereof.
As the substituted derivatives, for example, those carboxylated,
Alternatively, there is one made alkali-reactive. These compositions may be one kind or a mixture of a plurality of kinds. Examples of the composition of the styrene resin that constitutes the ink fixing layer include styrene-acrylic acid ester copolymer,
It is a styrene-methacrylic acid ester copolymer or a substituted derivative thereof. Examples of the substituted derivative include those that are carboxylated or those that have been rendered alkali-reactive. These compositions may be one kind or a mixture of a plurality of kinds. The rubber-based resin or styrene-based resin composition that constitutes the ink fixability is preferably an aqueous emulsion type such as latex. In the case of copolymerized latex containing styrene, the styrene polymerization ratio in the copolymerization component is 50 to 70%.
Use those. When the polymerization ratio is less than 50%, the coating film is soft and lacks in durability, and the swelling property due to a fluid component in the ink at the time of printing is deteriorated, and the ink fixability is deteriorated. If it exceeds 70%, the film formability is reduced and the coating film is hard and brittle. The thickness of the ink fixing layer is required to be about 1 μm, preferably about 5 to 10 μm. The main components of the ink fixing layer are rubber-based resins and styrene-based resins as described above, but other resin components (for example, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin) may be used depending on the need for heat resistance and scratch resistance. , Polyvinyl alcohol, fibrin derivative) and the like may be mixed. In order to prevent the films from sticking together when they are stacked, fine irregularities are formed on the film. The fine unevenness is formed by, for example, a granular material on the film surface. If particles having a particle size larger than the thickness of the ink fixing layer are mixed with the resin constituting the ink fixing layer, irregularities are formed on the surface of the film on the ink fixing layer side. Granules are mixed in a resin component (for example, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, polyvinyl alcohol, fibrin derivative) and coated on the side of the film opposite to the ink fixing layer side to form irregularities. May be. The irregularities of the granular material may be formed on both surfaces of the film by both of these methods. Examples of the granular material include silicon dioxide, calcium carbonate, magnesium carbonate, zinc oxide, aluminum hydroxide, titanium oxide, calcium silicate, aluminum silicate, mica, clay, talc, alumina, zinc stearate, calcium stearate, disulfide. Molybdenum, starch, polyethylene, polypropylene, polystyrene, acrylonitrile, methyl methacrylate,
Pigments such as tetrafluoroethylene, styrene-acrylic acid ester copolymer, phthalocyanine blue and red iron oxide. One type or a mixture of a plurality of types may be used. The shape of the granules is inconvenient if they are leaf-shaped, because they come into surface contact with the films to be stacked, and a spherical shape or a shape close thereto is preferable. The average particle size of the granular material is preferably about twice the thickness of the ink fixing layer. One type or a mixture of a plurality of types may be used. The amount of the granular material applied varies depending on the substance, but for silica, it may be about 5 mg / m ² or more. When the total amount of the particulate matter applied to both surfaces of the film increases, the finished film becomes translucent or opaque. The fine irregularities may be formed by processing the film surface itself. For example, the film may be embossed to form irregularities, or the film surface may be sandblasted to form irregularities. The conductive treatment applied to the plastic film preferably has a surface electric resistance of 10 ¹² Ω / □ or less. The plastic film is easy to be triboelectrically charged due to its electrical insulating property, and the lower the surface electric resistance, the less frictional electrification occurs, which makes it suitable as a printing film. However, in reality, its working environment (usually room temperature 20 ° C, relative humidity 60% ), If 10 ¹² Ω / □ or less, the charging is small and almost no tacking occurs, and even if it is further lowered to about 10 ⁸ Ω / □ or less, it does not change much in actuality. The surface electric resistance is based on the measurement specified in JIS, and two electrodes (1 cm long) are provided on the surface to be measured.
Are in close contact with each other at an interval of 1 cm, and the electric resistance between the two electrodes is measured. In order to reduce the surface electric resistance of the film, there is a method in which a resin or a conductive paint mixed with an antistatic agent is applied to the surface of the film opposite to the ink fixing layer. A conductive resin, for example, an anionic conductive resin into which a metal sulfonate or a metal carboxylate is introduced, a cationic resin into which a quaternary ammonium salt is introduced, or a siloxane resin is applied to the film to form a conductive film on the film surface. A layer may be provided. A conductive layer of metal or metal oxide can be provided on the film surface by sputtering or vacuum deposition. When a resin component containing particles is applied to the surface of the film opposite to the ink fixing layer to form irregularities, an antistatic agent or the like may be kneaded into the resin component. Further, in order to reduce the electric resistance of the surface of the film on the ink fixing layer side, an antistatic agent or the like may be kneaded into a resin composition constituting the ink fixing layer. Antistatic on the surface of such a film,
It may be applied to both sides of the film, but may be applied to only one side.
This is because when the films are stacked, one surface that is not subjected to antistatic contact with the antistatic surface of another film, and the electrostatic charge on that surface escapes. In order to lower the surface electric resistance of the film, an antistatic agent or the like may be kneaded into the film itself. [Operation] The printing film of the first invention and the second invention is provided with an ink fixing layer on the surface thereof, and has good adhesion (wetting) of the printing ink to the surface, absorbability and dry curability. For example, in offset printing inks, it is considered that the solvent component in the vehicle is absorbed or evaporated and the drying oil is oxidized and polymerized. I'm sorry. The ink is strongly retained in the ink fixing layer on the film surface, the solvent component is absorbed in the ink fixing layer, and the viscosity of the ink is sufficiently increased, so that the ink setting is fast and the drying and curing due to the oxidative polymerization of the drying oil is incomplete. Even if the films are stacked, they will not get dirty. The ink fixing layer using latex is formed in a state where fine particles having a particle size of 0.01 to 1 μm are maintained in the granular form. Therefore, there is a gap between the particles, so that the fluid component of the ink easily permeates, and the effective area to which the ink adheres is large. In addition, since the film has fine irregularities, air is retained in the gap. Therefore, even when the printed films are stacked, the printing ink comes into contact with the air to cause an oxidative polymerization reaction, which promotes drying and curing. Further, the fine unevenness formed on the films prevents the stacked films from sticking to each other, which improves the sliding property. Therefore, the registration accuracy of the printing machine is good, and after printing, they are perfectly aligned and stacked.
That is, the running performance is improved. Particularly, in the printing film of the second invention, since the surface electric resistance is 10 ¹² Ω / □ or less, the charging is small and the runnability failure due to tacking can be prevented. [Examples] Representative examples of the present invention will be described below. The comparative example is an example to which the present invention is not applied. Example 1-1 (Example of the first invention) 0.1% by weight using a reverse roll coater on one side of a transparent polyester film (Melinex 505 manufactured by ICI, England) having a thickness of 100 μm that has been subjected to easy-adhesion processing. Methyl methacrylate-butadiene copolymer latex (solid content 30% by weight) mixed with the silica powder (average particle size 10 μm) is coated and dried in a drying oven at 120 ° C. for 1 minute. An ink absorption layer of 7 μm of methyl methacrylate-butadiene copolymer latex was formed on the obtained film. Silica grains are projected on the ink absorption layer of this film to form unevenness on the entire surface. Example 1-2 (Example of the first invention) A transparent polyester film having a thickness of 100 µm (manufactured by Toray Industries, Inc., Lumirror Q-80) was embossed on one side with an embossing roll of fine satin finish. On the other side, apply methyl methacrylate-butadiene copolymer latex (solid content 30% by weight) using a reverse roll coater and apply 120 ° C.
The ink absorbing layer is formed by drying in the drying oven for 1 minute.
Unevenness due to embossing is formed on the opposite surface. Example 2-1 (Example of the second invention) One side of a transparent polyester film (Lumirror Q-80 Toray Co., Ltd.) having a thickness of 75 μm and subjected to an easy-adhesion processing treatment was coated with styrene-acryl Polymerized resin (Movinyl 86
A solution obtained by diluting a solid component (30% by weight) of water with a styrene polymerization ratio of 60% (available from Hoechst Synthetic Co., Ltd.) using a wire bar coater is applied, followed by drying with air. The resulting film had a styrene-acrylic copolymer ink absorption layer.
10 μm formed. A liquid having the following composition is applied by a reverse roll coater to the surface opposite to the surface on which the ink absorbing layer is formed. Nitrocellulose resin 15 parts by weight Sodium dodecyl phosphate 0.4 parts by weight Spherical cross-linked polystyrene (average particle size 6 μm) Fine Pearl 3000sp Sumitomo Chemical Co., Ltd. 1 part by weight Ethyl acetate 45 parts by weight Toluene 45 parts by weight A 3 μm thick antistatic layer was obtained. The antistatic layer has a surface electric resistance of 7 × 10 ¹⁰ Ω / □ at 20 ° C. and a humidity of 60%. Further, spherical cross-linked polystyrene is projected from the antistatic treatment layer to form irregularities. Example 2-2 (Example of the Second Invention) Carboxyl-modified styrene in which 2% by weight of silica powder (average particle size 10 μm) was mixed on one side of a 70 μm thick cellophane film using a reverse roll coater. A butadiene copolymer latex (solid content: 25%, styrene polymerization ratio: 55% in the copolymer component) is applied and dried by blowing. An ink absorbing layer of 6 μm of a carboxy-modified styrene-butadiene copolymer with protruding silica particles was formed on the obtained film. A liquid having the following composition is applied to the opposite surface by a reverse roll coater. Quaternary ammonium salt cation type acrylic resin (Sebian A830, solid content 30% by weight, manufactured by Daicel Chemical Industries, Ltd.) 3 parts by weight polymethylmethacrylate spherical fine particles (average particle size 6 μm)
10.2 parts by weight Methanol 70 parts by weight The coated surface was blow-dried at 120 ° C. for 1 minute to obtain an antistatic treatment layer having irregularities formed by polymethylmethacrylate particles. This antistatic treatment layer has a surface electric resistance of 5 × 10 ⁸ Ω / □ at a temperature of 20 ° C. and a humidity of 60%. Example 2-3 (Example of the Second Invention) A biaxially stretched polypropylene film having a thickness of 50 μm and having aluminum vapor-deposited on one surface thereof, was corona-treated on the surface not vapor-deposited on aluminum, and then gravure A roll coater is used to form a coating layer of 1 μm of chlorinated olefin resin for easy adhesion processing. A carboxy-modified methyl methacrylate-butadiene copolymer latex (solid content: 30% by weight) mixed with 3% by weight of talc powder (average particle size: 10 μm) is applied to this surface using a reverse roll coater, and dried by blowing.
An ink absorption layer of 6 μm of carboxy-modified methyl methacrylate-butadiene copolymer having irregularities due to silica powder was formed on this film. 20 ℃ of aluminum vapor deposition layer,
The surface electric resistance value at a humidity of 60% is 0.6Ω / □. Comparative Example 1 A solution having a solid content of 15% in which a vinyl chloride-vinyl acetate copolymer was dissolved in a mixed solvent of methyl ethyl ketone and toluene was applied to one surface of a transparent polyester film having a thickness of 100 μm using a reverse roll coater, followed by drying with air. . An 8 μm layer of vinyl chloride-vinyl acetate copolymer was formed on the film. The printing film obtained by each of the above examples is cut into a predetermined size to obtain a sheet-like film. The sheet-fed film is set on an offset printing machine to perform multicolor printing. The results are shown in the following table. Although Comparative Example 2 in the table is not described in detail above, it is a cellophane film having no ink fixing layer. The “print strength” in the table is judged as good or bad depending on the degree of peeling of the print when the adhesive tape is adhered to the print surface and peeled off vigorously. [Effects of the Invention] As described above, the printing film to which the present invention is applied has a good ink fixing property, and even if the films are stacked immediately after printing, they are not settling off and dirty. Since air is held in the gaps of minute unevenness formed on the film, even if printed films are stacked,
The oxidative polymerization reaction of the printing ink proceeds, and the printing strength increases. Since the ink fixing layer of this printing film has a high ink absorbing ability, it sufficiently absorbs even if a large amount of ink adheres. Therefore, it can be used not only for single-color printing but also for multi-color printing by taking advantage of offset printing. Also, since the fine unevenness does not cause the films to adhere to each other when the films are stacked, the running property is smooth, and the film is optimal for offset printing in a sheet-like film. In particular, the printing film of the second invention has excellent running properties. Further, since it has heat resistance and moisture resistance, it does not cause blocking, and also has excellent general properties as a printed film such as scratch resistance. The printed matter using the film of the present invention has excellent properties of beautiful finish and high print strength after printing.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroyoshi Midaigawa               1140 Kamiokutomi, Sayama City Dynic shares               Inside the Tokyo factory (72) Inventor Jun Arikawa               3-3-1 Higashiikebukuro, Toshima-ku, Tokyo               Tsuku Co., Ltd. Tokyo head office                (56) References JP-A-62-236786 (JP, A)                 JP-A-49-37705 (JP, A)                 JP 58-145489 (JP, A)                 JP 57-6787 (JP, A)                 62-236786 (JP, U)

Claims (1)

(57) [Claims] On at least one side of the plastic film, a styrene-butadiene copolymer, an acrylonitrile-butadiene copolymer, a methacrylic acid ester-butadiene copolymer, an acrylonitrile-styrene-butadiene copolymer, a methacrylic acid ester-styrene-butadiene copolymer. At least one rubber-based resin latex selected from a combination and a substituted derivative thereof, and / or at least one selected from a styrene-acrylic acid ester copolymer, a styrene-methacrylic acid ester copolymer, and a substituted derivative thereof. A printing film, which is provided with an ink fixing layer formed by applying various types of styrene-based resin latex as a main component, and has fine irregularities formed on at least one surface. 2. The printing film according to claim 1, wherein the fine irregularities are formed by a granular material on the film surface. 3. The fine irregularities are formed by the irregularities processed on the film surface.
The printing film according to the item. 4. On at least one side of the plastic film, a styrene-butadiene copolymer, an acrylonitrile-butadiene copolymer, a methacrylic acid ester-butadiene copolymer, an acrylonitrile-styrene-butadiene copolymer, a methacrylic acid ester-styrene-butadiene copolymer. At least one rubber-based resin latex selected from a combination and a substituted derivative thereof, and / or at least one selected from a styrene-acrylic acid ester copolymer, a styrene-methacrylic acid ester copolymer, and a substituted derivative thereof. An ink fixing layer containing styrene type resin latex as a main component is provided, fine irregularities are formed on at least any one surface, and at least any one surface is subjected to a conductive treatment. Printing film. 5. The printing film according to claim 4, wherein the fine irregularities are formed by a granular material on the film surface. 6. The fourth aspect is characterized in that the fine irregularities are formed by the irregularities processed on the film surface.
The printing film according to the item.